Conventionally, suture thread, adhesives, automatic anastomotic devices, staplers, clips or the like have been used to bond biological tissues together. However, suture thread is problematic in that, for instance, it takes time (in particular, fine sutures) and requires skill. Adhesives (for instance, fibrin pastes, cyanoacrylate or the like) are problematic, for instance, on account of low bonding strength and low safety (for instance, infectiveness in fibrin pastes and carcinogenicity in cyanoacrylate). Automatic anastomotic devices are difficult to employ in small sites, which is problematic, while staplers, clips or the like are problematic in that they require a long time for bonding.
Meanwhile, biological tissues can be coagulated/bonded to one another by using ultrasonic scalpels (vibration mode), but these scalpels require a horn for obtaining large vibration amplitudes, which makes device miniaturization difficult. Also, it is thought that bonding between biological tissues by ultrasonic scalpel arises from a partial fusion of the collagen matrix in the biological tissue, on account of the friction heat generated by the ultrasonic vibration of the scalpel blade. High-frequency scalpels allow bonding biological tissues together through heating (about 100° C.) brought about by the high frequency, but may inflict damage on the surroundings owing to the large size of the scalpel portion. Electrocautery scalpels (hemostasis mode) allow arresting hemorrhages by burning away biological tissue at a high temperature (300° C.), but it is difficult to bond biological tissues together using such electrocautery scalpels.
Meanwhile, angioplasty by way of stents is used for the therapy of stenosis in patients whose blood vessels are partially stenotic. Stent-graft implantation is performed for treating aortic aneurysm in patients whose aorta expands partially. Therapies using stents and stent-grafts involve extremely low-invasive procedures, since they require no thoracotomy, as is the case in artificial blood vessel replacement.
However, stents and stent-grafts are not sutured, and hence there may occur problems such as leakage of blood into the aneurysm on account of imperfect bonding with the artery (endoleaks), or drifting away from the implant site through the action of blood flow.